1. Field of the Invention
The invention is related to the field of three-point equipment, and in particular, to a suspension system for a three-point apparatus.
2. Statement of the Problem
Equipment manufacturers produce different equipment for use on the farm, in construction, in the yard, and in the garden. Some equipment is self-propelled, such as tractors, self-propelled sprayers, self-propelled combines, self-propelled lawn mowers, etc. Other equipment is pull-type, such as sprayers, cultivators, planters, etc. Pull-type equipment includes trailer-type units, three-point units, and a hybrid of the two.
Equipment, whether self-propelled or pull-type, may be used in fields, pastures, ditches, etc. The fields, pastures, and ditches may contain ruts, bumps, furrows, holes, and other conditions. Such conditions may damage the equipment over time. Equipment may also generate vibration from the engine, tires, power-take-off, etc. This vibration can also damage the equipment.
Some self-propelled units have a suspension to help protect the unit from damage and improve the ride for the operator when used in rough terrain. One example of a self-propelled unit with a suspension is the 284 XP sprayer from Hagie Manufacturing Company of Clarion, Iowa. The 284 XP sprayer has four wheels with an air spring between each one of the wheels and the frame of the sprayer.
A trailer-type unit is pulled by a tractor and includes a hitch and wheels. The wheels support the weight of the trailer-type unit. The hitch is configured to attach to a draw bar of the tractor so that the tractor can provide forward and backward movement of the unit. The draw bar of the tractor provides little to no support to the weight of the unit.
Fortunately, the flexibility of the attachment point between the tractor and the trailer-type unit helps absorb rough terrain encountered by the tractor. The attachment point helps isolate the trailer-type unit from the rough terrain and from vibrations of the tractor. Some trailer-type units include their own suspension. The suspension and tires of the trailer-type unit also help absorb the rough terrain encountered by the unit. One example of a trailer-type unit with a suspension is an Air Ride Suspension (ARS) trailer sprayer from Wil-Rich LLC of Wahpeton, N. Dak. The ARS trailer sprayer has two wheels with an air spring between each one of the wheels and the frame of the sprayer.
Three-point units are also transported with a tractor. Damage due to rough terrain can be especially a problem for three-point units. Unlike trailer-type units that have flexibility in the attachment point, three-point units are rigidly connected to three-point arms of a tractor with pins. In many three-point units, the three-point arms of the tractor support the entire weight of the unit.
For some three-point units, the only suspension between the three-point unit and the ground is the suspension of the tractor. When a tractor carrying the three-point unit encounters rough terrain, the rigid connection between the tractor and the three-point unit transfers movement of the tractor back to the unit. The movement of the tractor may be a bouncing or jarring movement. The rigid connection also transfers vibration from the tractor back to the three-point unit. The vibration may resonant in the three-point unit. The amount of movement and vibration may depend on whether the tractor has tires or tracks.
The turning radius of a three-point unit may also be a concern. A three-point unit rotates at a larger radius relative to the tractor turning radius in comparison to a trailer-type unit rotating about its attachment point. Fast turns and short correctional turns may add stress to the three-point unit.
One example of the three-point unit is a three-point sprayer from Wil-Rich LLC. In use, the rigid connection between the sprayer and the tractor transfers the movement of the tractor, due to the terrain, back to the sprayer. The movement due to the terrain may cause structural failure in the tank, the supporting structure, and/or the booms of the sprayer over time. This may be a greater concern as the sprayer booms get longer. The liquid in the tank of the sprayer may also slosh around exacerbating the problem. Vibration from the tractor may also damage the tank, booms, and frame over time.
Unfortunately, three-point units have not been effectively designed to reduce movement due to the terrain, vibration, and other damaging movements.